In mathematics, p usually stands for probability. Probability is a numerical value indicating the probability of something happening. Its value ranges from 0 to 1, where 0 means impossible and 1 means inevitable. In probability theory, we use a series of formulas and methods to calculate the probability of various events. For example, when you flip a coin, the probability of both sides is 0.5, because they are equal possible events.

In statistics, P value is an important index to test whether the hypothesis is true. Hypothesis test is a scientific method to infer the overall characteristics by observing the sample data. When we test a hypothesis, the value of p indicates how much evidence we have to support this hypothesis. If the p value is very small (usually less than 0.05), then we think that the hypothesis is not established; On the other hand, if the p value is large (greater than 0.05), we can't deny this hypothesis.

Besides, in mathematics and physics, P also stands for momentum. Momentum is a vector, which indicates the motion state of an object. The magnitude of momentum is equal to the mass times the velocity of the object. According to the law of conservation of momentum, when objects collide, their total momentum remains unchanged. Therefore, momentum is a very important concept in physics and has a wide range of applications.